Method of dehydrogenation, dehydrocyclization and hydrodealkylation

ABSTRACT

Method for the dehydrogenation or dehydrocyclization of paraffins, for dehydrogenation of olefins with from 2 to 20 carbon atoms, and for hydrodealkylation of naphthalene homologs at temperatures ranging from 300* to 650*C on a catalyst comprising a palladium base alloy containing rhenium, tungsten and combination tungsten and ruthenium. The method can find application in the production of monomers, such as isoprene, for synthetic materials, pharmaceuticals, in processing petroleum hydrocarbons and natural gas.

United States Patent [191 Smirnov et a1.

METHOD OF DEHYDROGENATION, DEHYDROCYCLIZATION AND HYDRODEALKYLATIONInventors: Viktor Sergeevich Smirnov,

Filed:

Kutuzovsky prospekt, 26, kv. 555; Vladimir Mikhailovich Gryaznov,Leninskie Gory, MGU, Zona L, kv. l 10; Valentina lvanovna Lebedeva,

. Leninsky prospekt, 48a, kv. 29;

Alexandr Petrovich Mischenko, Khersonskaya ulitsa, 7, korpus 4, kv. 115;Victoria Petrovna Polyakova, ulitsa Trofimova, l5, kv. 201; EvgenyMikhailovich Savitsky, ulitsa Dm. Ulyanova, DNR-3, kv. 13, all ofMoscow, U.S.S.R.

July 12, 1972 Appl. No.: 271,186

Related U.S. Application Data Division of Ser. No. 23,037, March 26,1970,

abandoned.

U.S. Cl...- 260/680 R, 48/198, 48/D1G. 5, 260/668 D, 260/672 R, 260/6735lnt. C1. C07C 11/12 Field of Search 260/6833, 680 R; 252/470,

48/198, 199, DIG. 5

[111 3 ,865,891 [451 Feb. 11, 1975 [56] References Cited UNITED STATESPATENTS 3,198.604 8/1965 Pfe fferle 423/648 3 90,406 12/1966 Pfelferle3,344,582 10/1967 Merrill et a1 3,375,288 3/1968 de Rosset 3,562,3462/1971 Smimov et a1 260/6735 Primary Examiner-C. Davis Attorney, Agent,or Firm-Holman & Stern 13 Claims, No Drawings The present application isa divisional application of copending application Ser. No. 23,037, filedMar. 26, 1970, now abandoned.

The present invention relates to processing of hydrocarbons, and moreparticularly to a method of dehydrogenation or dehydrocyclization ofparaffins, dehydrogenation of olefines with from 2 to 20 carbon atoms,and for hydrodealkylation aromatic hydrocarbons, which are carried outeither separately or simultaneously. Such method can find applicationwhen producing monomers for synthetic materials, pharmaceutical andother synthetic semiproducts, when processing petroleum hydrocarbons andnatural gas, vegetable oils, and also for producting ultrapure hydrogen.

The known methods, industrially employed for processing hydrocarbons,use the catalysts in the form of blacks, powders and granules,comprising, as a rule, a mixture of two or move substances, or they areapplied onto supports, for example, nickel or platinum onto aluminiumoxide. Such catalysts cannot be employed as membrane catalysts, that is,permselective for hydrogen, and they do not allow simultaneous runningof dehydrogenation and hydrodealkylation processes without mixing thestarting substances. These processes are more expedient to be carriedout with the catalyst being used as a partition permselective forhydrogen only, so that on one side of the partition there should takeplace the process with elimination of hydrogen, and on the other sidethereof, the process of addition of the hydrogen that has passed throughthe partition. Earlier it has been proposed that palladium alloyscomprising at least one of the rest of the elements belonging to groupVlll of the Periodic System as well as copper, silver, gold or boronshould be used as such a partition or membrane catalyst (cf. French Pat.No. 1,579,529).

The use of these catalysts has shown them to possess sufficiently highactivity and selectivity for carrying out the processes.

An object of the present invention is to provide a method for thedehydrogenation or dehydrocyclization of olefins and for thehydrodealkylation of naphthalene homologs which is free of theaforementioned and other such disadvantages and, specifically, comprisescontacting the feedstock with a catalyst based on palladium alloys whichare highly thermostable and selectively permeable to hydrogen.

Said and other objects of the invention are accomplished by using amethod for the dehydrogenation or dehydrocyclization of paraffins,dehydrogenation of olefins with from 2 to 20 carbon atoms, and forhydrodealkylation of naphthalene homologs at temperatures ranging from'300 to 650C with a catalyst comprising a palladium base alloy containinga metal selected from the group consisting of rhenium, tungsten andcombinations of tungsten and ruthenium, the content of pa]- ladium issaid alloy being in the range of from 60 to 99 weight percent. Thefollowing combinations of the said components in the alloy are possible.An alloy comprising 80 to 99 weight percent of palladium and l to 20weight percent of rhenium; a more specific composition is an alloycomprising 95 weight percent of palladium and 5 weight percent ofrhenium. Other combinations of said components in the alloy are featuredby an alloy comprising 80 to 99 weight percent of palladium and 1 to 20weight percent of tungsten, and also by an alloy comprising to 97.5weight percent of palladium, 2 to 20 weight percent of tungsten and 0.5to 5 weight percent of ruthenium.

A more specific composition of the alloy is that comprising 94 weightpercent of palladium, 5 weight percent of tungsten and 1 weight percentof ruthenium.

Said catalysts can be used either in a conventional fashion, that is, asa powder or black, or a gauze, or, else. as partitions, such asmembranes, films, foils and tubes which are permselective for hydrogen.

The introduction of rhenium or tungsten into the composition of thepalladium alloy allows to enhance the thermal stability of the catalyst,which is essential for the heat threatment of the catalyst in theprocess of its regeneration. Moreover, the processing of alkanes withthe number of carbon atoms greater than six on these alloys makes itpossible to obtain mainly benzene. obviating the stage of dealkylationof alkyl aromatics.

The introduction of ruthenium into the alloy comprising palladium andtungsten allows a material increase in the yield of isoprene whendehydrogenating 2-methylbutenel.

The conversion process can be carried out either with the puresubstances, or in a stream of helium or argon in a silica reactor, intowhich the catalyst is placed.

For a better understanding of the invention, some examples are givenhereinbelow by way of illustration. In all the examples that follow therate of passage is 30 nil/min. The reaction products were analyzedchromatographically.

EXAMPLE 1. g

DEHYDROGENATION OF Z-METHYLBUTENE-l Dehydration of Z-methylbutene-l toisoprene is carried out at a temperature ranging from 300 to 500C. Thecatalyst is a foil made of palladium alloy comprising 5 weight percentof tungsten and 1 weight percent of ruthenium. The weight of thecatalyst is 0.975 g, total surface area, 33 sq.cm.

Given in Table 1 below is a temperature dependence of the yield ofisoprene and other reaction products in volume percent to thehydrocarbon passed.

3 4 With the temperature rising from 300 to 440C, the Given in Table 4below is the temperature depenyield of isoprene increases and reaches28.l percent. dence of the yield of benzene and toluene in volume With afurther increase of the temperature the yield percent to the heptanepassed. of isoprene diminishes. The most optimal temperature is 440C. 5Table 4 EXAMPLE 2. DEHYDROGENATION OF CYCLOHEXANE T0 S 1 35? "55%? "3351BENZENE Dehydrogenation of cyclohexane to benzene is car- 588 21.9 70.28.0

ried out at temperatures ranging from 300 to 500C on 625 341 14.4 415the catalyst which is the palladium alloy including 5 weight percent oftungsten and 1 weight percent of ruthenium as stated in Example 1.Listed in Table 2 5 With an increase in the temperature, the yield ofarobelow is the yield of benzene depending on the tempermatichydrocarbons becomes greater and reaches 48.5 ature in the reactor.volume percent at 625C.

Table 2 Benzene vol.% 17.8 19.4 21.3 31.2 32.6 35.9 41.5 45.7 51.4

EXAMPLE 3. EXAMPLE 5.

DEHYDROCYCLIZATION OF OCTANE Dehydrocyclization of octane is carried outat tem- Dehydrocycllzatlon of heptane to toluene and benperamres rangingfrom to 550C, on a catalyst DEHYDROCYCLIZATlbN OF HEPTANE zene iscarried out at temperatures ranging from 450 f th to 590C on a foilcatalyst made of the palladium alloy 2521212? weght of including 5 lPercent il l and 1 Weight Listed in Table 5 below is the yield ofbenzene in volpercem of ruthemum as Speclfied m Example ume percent,depending on the temperature in the re- Listed in Table 3 below is theyield of toluene, ben- 35 actor zene and other reaction products involume percent,

depending on the temperature. Table 5 tfC Benzene Octane Otherhydrocarbons vol.% vol.% vol.% Table 3 40 455 2 9 97.0 traces 493 9.388.2 2.4 t,C Methane Hexane Heptane Benzene Toluene 528 12.4 84.8 2.8vol.% vol.% vol.% vol.% vol.% 551 I6 5 79.7 3.8

450 4.7 89.8 5.4 traces 460 8.3 4 82.7 9.0 traces EXAMPLE 6. 487 13.070.3 14.3 2.3 500 15.3 50.3 17.2 17,2 HYDRODEALKYLATION OF TOLUENE 51118.0 46.1 19.8 16.2 525 ,7 traces 52 2L6 Hydrodealkylatlon of toluene tobenzene 1s carrled 233 $3: 33-; 2-3 out at temperatures ranging from 320to 680C. The 5 catalyst is a foil of an alloy of palladium with 5 weight580 28.6 tra es 15.6 52.9 2.9 percent of rhenlum. The weight of the fol]ls 3.3 lg; the 590 total surface area is 55 sq.cm.

Listed in Table 6 below is the yield of benzene and other reactionproducts, in volume percent to the tolu- Maxlmum yleld of aromatlchydrocarbons ls attalned 55 ene passed depending on the temperatureconditions. at a temperature of 590C, being 57.3 volume percent.including the yield of benzene which amounts to 54.7 Table 6 volumepercent.

1C C H, C H Benzene Toluene vol. vol.% vol.% vol.% EXAMPLE 4.

32l 7.l 4.2 2.9 85.7 DEHYDROCYCLlZATION OF HEPTANE 337 6.2 6.2 3.1 84.4g 355 11.5 10.0 3.5 75.0 Dehydrocylization of heptane to benzene andtczlu- 1 38:3 :22 if ene is carried out at temperatures ranglng from 500to 462 25.3 21.7 4.9 411.1 625C. The catalyst is a foil from an alloyofpalladium 2 ig-g a; 32-5 with 5 weight percent of rhenium. The weightof the 597 2&2 225 33 404 671 39.7 25.8 21.5 13.0

catalyst is 3.3lg, its total surface area is 55 sq.cm.

As can be seen from the Table, with an increase in the temperature theyield of benzene increases and reaches 21.5 volume percent at 671C.Unlike the case with the catalysts proposed heretofore, (cf.French Pat.No. 1,579,529), on the alloy of palladium with rhenium the conversion oftoluene to benzene is observed already at a temperature of 321C.

EXAMPLE 7.

HYDRODEALKYLATION of l,6-D1METHYLNAPHTHALENE Hydrodealkylation ofl,6-dimethylnaphthalene to methylnaphthalenes and naphthalene is carriedout at temperatures ranging from 461 to 624C on a foil of an alloy ofpalladium with 5 weight percent of rhenium. The weight of the catalystis 3.3lg, total surface area is 55 sq.cm. The temperature dependence ofthe yield of napthalene, a-methylnaphthalene, B-methylnaphthalene andmethane, in volume percent to the The total yield of methylnaphthalenesand naphthalenes reaches 24.8 percent at a temperature of 568C.

EXAMPLE 8.

DEHYDROGENATION OF Z-METHYLBUTENE-l The catalysts used were palladium inan alloy with 5 weight percent, weight percent, and weight percent oftungsten. The temperature of the dehydrogenation reaction was 445C. Thesurface area of the catalyst samples made as foils was 62sq cm. Listedin Table 8 below is the yield of isoprene, in volume percent whendehydrogenating 2-methylbutene-l, depending on the alloy composition.

Table 8 Composition 5 Weight 10 Weight 15 Weight of Alloy of Tungsten ofTungsten of Tungsten lsoprene vol. percent 4.2 5.3 8.2

Thus, as can be seen from the disclosure, the new method proposedherein, as regards the activity and selectivity of catalysts are notinterior to, and in some cases even excel the catalysts proposedheretofore. Due to the fact, that said palladium alloys feature agreater thermostability, their application proves to be especiallydesirable in those cases when the processes are carried out at hightemperatures. and in the course of regeneration the catalysts aresubject to an intense heat treatment.

What is claimed is:

l. A method for the selective preparation of dienes which comprises thepassing of a vaporized hydrocarbon feedstock at a temperature of 300 to650C over a catalyst consisting of palladium alloyed with at least onemember of the group consisting of rhenium, tungsten, and a combinationof tungsten and ruthenium, the content of palladium in said alloyranging from 60 to 99 weight percent, said feed-stock being a C -Colefin which is thereby subjected to dehydrogenation.

2. A method according to claim 1 wherein said catalyst comprises analloy of from to 99 weight percent of palladium and from 1 to 20 weightpercent of rhenium.

3. A method according to claim 2 wherein said catalyst comprises 95weight percent of palladium and 5 weight percent of rhenium.

4. A method according to claim 1 wherein said cata lyst comprises analloy of from 80 to 99 weight percent of palladium and from 1 to 20weight tungsten.

5. A method according claim 4 wherein said catalyst comprises 95 weightpalladium and 5 weight percent tungsten.

6. A method according claim 4 wherein said catalyst comprises 90 weightpercent palladium and 10 weight percent tungsten.

7. A method according to claim 4 wherein said catalyst comprises weightpercent palladium and 15 weight percent tungsten.

8. A method according to claim 1 wherein said catalyst comprises analloy of from 75 to 97.5 weight percent palladium, from 2 to 20 weightpercent of tungsten and from 0.5 to 5 weight percent ruthenium.

9. A method according to claim 8 wherein said catalyst comprises 94weight percent of palladium, 5 weight percent tungsten and 1 weightpercent of ruthenium.

10. A method for dehydrogenation of 2- methylbutene according to claim 1at temperatures ranging from 300 to 500C on a catalyst which comprisesan alloy of 94 weight percent palladium, 5 weight percent tungsten and 1weight percent of ruthenium.

11. A method according to claim 1 wherein said catalyst comprises analloy of palladium with from 5 to 15 weight percent tungsten.

12. A method according to claim 1 wherein said catalyst comprises anarticle manufactured in a form which is selectively permeable tohydrogen only.

13. A method according to claim 12, wherein hydrogen is produced by thereaction, said catalyst is in the form of a membrane, and said hydrogenis withdrawn through the said membrane catalyst.

1. A METHOD FOR THE SELECTIVE PREPARATION OF DIENES WHICH COMPRISES THEPASSING OF A VAPORIZED HYDROCARBON FEEDSTOCK AT A TEMPERATURE OF 300* TO650*C OVER A CATALYST CONSISTING OF PALLADIUM ALLOYED WITH AT LEAST ONEMEMBER OF THE GROUP CONSISTING OF RHENIUM, TUNGSTEN, AND A COMBINATIONOF TUNGSTEN AND RUTHENIUM, THE CONTENT OF PALLADIUM IN SAID ALLOYRANGING FROM 60 TO 99 WEIGHT PERCENT, SAID FEED-STOCK BEING A C2-C20OLEFIN WHICH IS THEREBY SUBJECTED TO DEHYDROGENATION.
 2. A methodaccording to claim 1 wherein said catalyst comprises an alloy of from 80to 99 weight percent of palladium and from 1 to 20 weight percent ofrhenium.
 3. A method according to claim 2 wherein said catalystcomprises 95 weight percent of palladium and 5 weight percent ofrhenium.
 4. A method according to claim 1 wherein said catalystcomprises an alloy of from 80 to 99 weight percent of palladium and from1 to 20 weight tungsten.
 5. A method according claim 4 wherein saidcatalyst comprises 95 weight palladium and 5 weight percent tungsten. 6.A method according claim 4 wherein said catalyst comprises 90 weightpercent palladium and 10 weight percent tungsten.
 7. A method accordingto claim 4 wherein said catalyst comprises 85 weight percent palladiumand 15 weight percent tungsten.
 8. A method according to claim 1 whereinsaid catalyst comprises an alloy of from 75 to 97.5 weight percentpalladium, from 2 to 20 weight percent of tungsten and from 0.5 to 5weight percent ruthenium.
 9. A method according to claim 8 wherein saidcatalyst comprises 94 weight percent of palladium, 5 weight percenttungsten and 1 weight percent of ruthenium.
 10. A method fordehydrogenation of 2-methylbutene according to claim 1 at temperaturesranging from 300* to 500*C on a catalyst which comprises an alloy of 94weight percent palladium, 5 weight percent tungsten and 1 weight percentof ruthenium.
 11. A method according to claim 1 wherein said catalystcomprises an alloy of palladium with from 5 to 15 weight percenttungsten.
 12. A method according to claim 1 wherein said catalystcomprises an article manufactured in a form which is selectivelypermeable to hydrogen only.
 13. A method according to claim 12, whereinhydrogen is produced by the reaction, said catalyst is in the form of amembrane, and said hydrogen is withdrawn through the said membranecatalyst.